Field of the Invention
The present invention relates to a method and an apparatus for transmitting power wirelessly.
Discussion of the Related Art
In recent years, with the development of communication and information processing technology, use of smart devices such as a smart phone, and the like has gradually increased and at present, a charging scheme generally applied to the smart devices is a scheme that directly connects an adapter connected to a power supply to the smart device to charge the smart phone by receiving external power or connects the adapter to the smart device through a USB terminal of a host to charge the smart device by receiving USB power.
In recent years, in order to reduce inconvenience that the smart device needs to be directly connected to the adapter or the host through a connection line, a wireless charging scheme that wirelessly charges a battery by using magnetic coupling without an electrical contact has been gradually applied to the smart device.
There are several methods for wirelessly supplying or receiving electric energy and representative methods include an inductive coupling scheme based on an electromagnetic inductive phenomenon and an electromagnetic resonance coupling scheme based on an electromagnetic resonance phenomenon based on a wireless power signal of a specific frequency.
In both schemes, data is transmitted and received by forming a communication channel between a wireless charging apparatus and an electronic apparatus such as the smart device to secure stability in power transmission and increase transmission efficiency. A phenomenon may occur, in which the power transmission is interrupted due to noise generated in the communication channel or a power receiving apparatus moves while wirelessly transmitting power, and as a result, transmission efficiency may deteriorate.
In particular, even in a multiple coil wireless power transmission scheme, since a primary coil for the power transmission is selected as one-time recognition operation at the time of first recognizing a receiving apparatus, even though relative positions of a transmitting apparatus and the receiving apparatus are changed, power is just transmitted with low efficiency through the primary coil which is first recognized even after.